Electric soldering iron



INVENTOR.

2 Sheets-Sheet 1 A. SCHOENWALD ELECTRIC SOLDERING IRON Patened May 29, 1.951y

ELE CTRIC SOLDERING IRON Alexander Schoenwald, Binghamton, N. Y., as- 'signor to Instant Tool Corporation, a' corporation of New York Application October 5, 1948, Serial No. 52,907

This invention relates to an electrically heated device and while the 'invention is' particularly adaptable in construction of electric'soldering iifo'ris, it will be understood that it is not lrestricted to such a device but may be incorporated in the construction of any device which is heated through the medium of a current of electricity passed through a resistance coil.`

O ie object of the invention is to provide an electrically heated soldering iron or equivalent device formed of special materials and of such construction that it will be quickly heated to a desired temperature for use and maintained at such temperature with a minimum amount of current.l

Another object of the invention is to provide a soldering iron having an improved tip heated by current flowing through front and rear coils, one` being formed of aY high resistance metal having a lower thermal co-efci'ent than the secondv which has a high temperature co-enicient but a lower heat resistance and thus obtain at'the start a high impact heating power and materially reduce the heating-up time;`

Another object of the invention is to provide a soldering iron formedl of such materials that it will havey a high stability against oxidation at hi'r temperatures and also have good resistance to hernical'corrosions often caused by luxin'g when soldering irons' of conventional formation are used;

Another object of the invention is to provide av soldering iron of such construction that flow of heat to its handle will be effectively resisted and overheating of the handle thus avoided.

' Another object of the invention is to provide an 'electric soldering iron which is of simple and compact construction and is provided with a switch` by means of which flow of current through its 'coils may be shut oil when so desired.

The invention is illustratedin the accompanying* drawings wherein:

Figure 1 is a side elevation of the improved soldering iron.

Figure 2 is a view looking down upon Figure l.

yFigure 3n is a sectional view taken longitudinallygthrough the improved soldering iron.

vligure/i is a sectional view upon an enlarged scal'e' taken longitudinally through the tip of the soldering ironrupon the line .4 4 of Figure 5.

Figure 5 is a 4sectional view taken transversely throughthe tip upon theline 5 5 of Figure 4.

Figure 6 is a transverse sectional view taken along the line 6 6 of Figure 1.

Figure 7 isatransverse sectional view taken along the liney 1 1 of Figure 3.

2 `Claims. (Cl. 2l9 26) Figure 8 is a transverse sectional view taken along the line 8 8 of Figure l.

Figure 9 is atransverse sectional view taken along the line 9 9 of Figure 3.

This improved soldering iron has a tip I, a tubular tip holder 2, and a handle 3. The tip is of a ilat blade-like formation, as shown in Figures 1 and L2, so that solder may be applied in narrow crevices and has a shell 4 which is formed of an active metal and is preferably nickel or its alloys. Within the s hell is a llining o r temperature adjuster 5 formed of metal or other suitable material having higher heat conductivity properties than the metal from which theshell is formed. The metal from which the lining is formedv is normally solid but will be liquefied when subjected to predetermined temperature in order to make use of its fusion heat andits resultant raised heat conductivity. The next layer 8 is formed of mica, magnesium oxide, or other suitable insulating material having high heat resistant properties. The sleeve 6 encloses a heating coil 'I formed of resistance wire having `low temperature co-eiiiciency and this heating unit is coiled about a core 8 which is formed o'f high heat resistance insulating material and extends longitudinally in the pocket deiinedl by the sleeve 6 and has a tapered front end. This core is hollow and into it litsv the forward portion of an electrode 9 which passes longitudinally through a bore formed centrally of a body l0 of insulating material such as ceramic,` sintered mica, magnesium oxide and the like having .high heat resistance qualities. The rear endY of the sleeve fits into'a pocket Il formed in the front end of the body I0 and the vrear portion of the shell 4 projects beyond the rear endof the sleeve and nts snugly about the body' with its rear end abutting an annular shoulder I2 extending about thev body circumfereritia-lly thereof.

About the rear end of the body is formed a circumferentially ,extending shoulder I3 and aboutv the portion of the body between the should ers `iZ-"and I3 is a second coil I4 formed of resistance wire having high Itemperature co-eiiic iency and connected in seriesfwith the coil l bvaconnection 'I5 whichpassed through an opening 'I6 'extending longitudinally through the body at theincline shown in Figure 4. Ar sleeve I l ,of insulation surrounds the coil I4 and in order'to prevent rear' portions of the resistance wire andthe electrode frorn slipping longitudinally andto form tight joints about them there hlas been provided.V packing 'L8 formed of heat resistent Clement- .It Shoild be noted that @,X-

tremities of the electrode 9 and the wire forming the coil I4 protrude from the cement I8 and form terminals 9 and III and that the front end I9 of the wire forming the coil i passes through a side opening formed in the sleeve 6 and is attached to the front end of the electrode 9. The tip I is passed longitudinally through the centrally located bore of a metal block 2l which is mounted in the forward portion of the tip holder 2 and secured by screws 22. Set screws 23 which are threaded through the block firmly hold the tip against longitudinal movement out of a set position and ends of these set screws are exposed through openings in the tip holder so that they may be tightened and also loosened when necessary. 1

The handle 3 has a body 24 formed of wood or other suitable material which is a poor conductor of heat and about this body iits a sleeve 25 formed of plastic high tensile strength. A chamber 2S extends longitudinally in the handle and from the rear end of this chamber extends a passage 2l to accommodate a power cable 28, the rear end of the handle body and its cover 25 being reinforced by a metal thimble 29 which fits into the extended rear end portion of the cover and is secured therein by screws 30. The handle is also formed with a transversely extending opening 3l into one end portion of which is driven a plug 32 having engagement with the cable to prevent the cable from being torn loose if subjected to outward pull. rThe handle is also formed with a side opening near its front end through which is mounted a switch 33 and the sleeve is formed with a slot 34 leading from its front end to accommodate the switch and allow the sleeve to be slid forwardly into place about the handle body. The wires 28' of the power cable are connected with the terminal 9' and one terminal of the switch and the other terminal of the switch is connected with the terminal I4 by a conductor wire 35 which may be a strand of wire cut from one of the wires 28. When the switch is closed current flows through the resistance coils and this causes the tip to be heated. rfhe tip has an improved thermal efficiency due to the exceptionally short heat conduction space between the source of heat and the heating surface. In addition, the relatively thin wall thickness of the active nickel shell overcomes its poorer heat conductivity in comparison to copper. The best efficiency can be achieved when the wall thickness of the shell is less than of the shortest diameter measured cross section of the tip.

A collar 3B which is formed of high heat insulating material is secured about the front end of the handle by screws 31 and to this collar a disk 38 of greater diameter than the collar is secured by screws 39. The disk is formed of high heat insulating plastic and its center opening and the chamber 26 with which it registers are of such diameter that the rear end portion of the tubular tip holder 2 will be spaced therefrom when iitted into the handle. A metal flange or disk d@ is spaced forwardly from the rear end of the tube 2 and through this disk are passed screws ^lI which ycarry spacer sleeves 42 and are passed through the disk 38 and engaged in threaded sockets formed in the collar 36. The spacers are formed of ceramic or other suitable high heat insulating materials and the screws are formed of metal having a lower heat conductivity than steel or iron. The soldering iron may, therefore, be conveniently held by its handle without inconvenience when it is in use and its tip will be quickly heated to a desired temperature when the switch is closed. As the switch is located near the front end of the handle it may be readily operated by the thumb of the hand grasping the handle.

From the foregoing description of the construction of my improved device, the operation thereof and the method of assembly will be readily understood, and it will be seen that I have provided a comparatively simple, inexpensive and efficient means for carrying out the Various objects of the invention.

While I have particularly described the elements best adapted to perform the functions set forth, it is apparent that various changes in form, proportion and in the minor details of construction may be resorted to, without departing from the spirit or sacrificing any of the principles of the invention.

Having thus described the invention, what is claimed is:

l. In an electrically energized soldering iron, a handle, a tubular tip holder projecting forwardly from said handle, a tip mounted in said holder and projecting forwardly therefrom, said tip being flat in cross section and of appreciably greater width than thickness and including a shell formed of thin metal and having a closed and pointed front end, a lining for the forward portion of said shell formed of a solid metal which fuses on heating the tip to a soldering temperature, a sleeve of insulation in said shell surrounded by and having close fitting engagement with said liner, a core of insulating material extending longitudinally in said sleeve axially thereof and having a bore leading from its rear end, a body of insulation fitting in the rear portion of said shell and having its front end surrounding the rear end of ysaid sleeve and abutting the rear end of the lining and being formed with a bore aligned with the bore of said core, an electrode extending longitudinally in the bores of the core and the body, front and rear coils surrounding the core and the body and connected in series, the front coil having its front end connected with the front end of said electrode, and power wires extending longitudinally through said handle and said tip holder and being one connected with the electrode and the other with the rear coil.

2. In an electric soldering iron, a hollow handle, a tubular tip holder projecting forwardly from said handle, a tip projecting forwardly from said tip holder, said tip having an elongated metal shell closed at its front end, a lining for said shell formed of a solid metal which fuses on heating the tip to a soldering temperature, a core extending longitudinally in said shell and formed with a longitudinal bore, a sleeve of insulation surrounding said core and having close fitting engagement with said lining, a body of insulation fitting into the rear portion of said shell and about the rear end of the sleeve, an electrode extending longitudinally through said body and fitting into the bore of said core, a heating coil about said core surrounded by said sleeve and having its front end connected with said electrode, and power wires extending longitudinally through the handle and the tip holder and connected with the electrode and the coil.

ALEXANDER SCHOENWALD.

(References on following page) REFERENCES CITED v The following references are of record in the flle of this patent:

UNITED STATES PATENTS` Number Name Date Weston July 17, 1888 Grutting July 7', 1896 Berry June 12, 1917 Kuhn July 3, 1917 Clark et al May 17, 1921 Simon Dec. 30, 1924 Post Feb. 10, 1925 Number Number Name Date Jarkovsky Oct. 5, 1926 Rapelye May 31, 1921 Hazlett et al Oct. 13, 1931 Bennett Jan. 22, 1935 Stackhouse July 28, 1936 Abbott Dec. 10, 1940 Grey Sept. 30, 1941 FOREIGN PATENTS Country Date Great Britain June 17, 1943 

